[M.D. Holloway]

IBM claims major boost in solar cell efficiency
John Walko
EE Times Europe
(05/16/2008 10:57 AM EDT)


LONDON — IBM has managed to squeeze 230W of power on to a centimeter square of solar panel using concentrator photovoltaics. The energy was then converted to 70W of usable electric power, the best power efficiency yet achieved, the company claims.
The IBM researchers used a very thin layer of a liquid metal made of a gallium and indium compound that they applied between the chip and a cooling block. Such layers, called thermal interface layers, transfer the heat from the chip to the cooling block so that the chip temperature can be kept really low.

They suggest that if the silicon can be cooled effectively, concentrated photovoltaics could take over as the cheapest form of solar energy.

However, IBM admits there is much work to be done to move the research project from the lab to the fab.

By using a much lower number of photovoltaic cells in a solar farm and concentrating more light on to each cell using larger lenses, IBM's system enables a significant cost advantage in terms of a lesser number of total components.

The researchers said that the concentration increases the power of the sun's rays by a factor of ten, allowing cells that normally generate 20W of power to generate 200W instead.

Their initial results were presented at this week's 33rd IEEE Photovoltaic Specialists conference , where the researchers showed how their liquid metal cooling interface is able to transfer heat from the solar cell to a copper cooling plate much more efficiently than anything else available today.

"We believe IBM can bring unique skills from our vast experience in semiconductors and nanotechnology to the important field of alternative energy research," said Dr. Supratik Guha, the scientist leading photovoltaics activities at IBM Research. "This is one of many exploratory research projects incubating in our labs where we can drive big change for an entire industry while advancing the basic underlying science of solar cell technology."

The researchers developed a system that achieved the "breakthrough" results by coupling a commercial solar cell to an IBM liquid metal thermal cooling system using methods developed for the semiconductor industry.

IBM adds that concentrator-based photovoltaics technologies have the potential to offer the lowest-cost solar electricity for large-scale power generation, "provided the temperature of the cells can be kept low, and cheap and efficient optics can be developed for concentrating the light to very high levels."

IBM is not planning to make solar cells itself, but expects to license the technology, and potentially its lens technology as well, to solar equipment manufacturers.

The company is also developing nanotechnology structures, involving nanowires and quantum dot semiconductors, to make photovoltaic cells more efficient.

Someday a Traga roof replacement?